Water for second dwelling unit

[audaxone]

I live in Ontario, Canada, and have a well that pumps about 4gpm. My pressure tank (80gal) is adequate for the needs of our house.

However, I am adding a small second dwelling unit (with kitchenette, bathroom, shower, and potential laundry) and I am concerned about losing water pressure and volume at the house when the second unit uses water.

Should I add a bigger pressure tank at the house, add a second pressure tank, or some other option?

 

[Reach4]

Same altitude for both?

Are you looking to give the house priority?

Is the pump submersible (down the well)?

A second pressure tank at the house is not going to help. What if the tank is almost empty, and the pressure is just above the turn-on pressure when both housed decide to fill the tub?

I would not like to have to add an atmospheric tank with a separate pressure pump, but that would take care of worst-case scenarios.

 

[Sponsor]

 

[audaxone]

Yes, same altitude. Second dwelling unit is about 50ft from the house.

Yes, the house would have priority.

Yes, the pump is submersible.

No tub in the second unit, only sink and shower for now. Potentially laundry in the future. It is never going to use a lot of water. I was thinking a little more volume would smooth out same time use issues.

 

[Valveman]

An 80 gallon pressure tank only holds 20 gallons of water. But that is still large enough to keep a 4 GPM pump from cycling too much, even when supplying two houses. But the 4 GPM pump is not enough for 2 houses. You can either switch to a 10 GPM pump in the well or use the 4 GPM pump to fill a cistern, then you can supply multiple houses with the booster pump in the cistern.

 

[Reach4]

Yes, same altitude. Second dwelling unit is about 50ft from the house.

Yes, the house would have priority.

It seems to me that you could have a solenoid valve that sends water to the second house when the pressure in the first house is above say 35 PSI. Then use a 40/60 pressure switch to control the pump.

A pressure tank in the second house, fed via a check valve, could perhaps hide some outages.